Charging ahead: Paving a safe path for battery energy storage systems
At a glance
The global energy transition is driven by the potential of battery-based solutions, including battery energy storage systems (BESS) and electric vehicles (EVs). These technologies are pivotal in reducing reliance on fossil fuels and achieving our net-zero carbon targets.
Beyond common applications for battery technology, like electric cars, and electric bikes, batteries are deeply embedded in many aspects of modern life, including in our smartphones and laptops as well as power tools like cordless drills.
Today, batteries traverse continents and oceans, are often stored in bulk at ports and in warehouses, becoming central to utility-scale storage systems, – or 'big batteries' – that help stabilise our power grids.
As we adopt battery technology more widely, it is essential to address the unique challenges they present, particularly the safety hazards associated with lithium-ion batteries (LIBs), given their increasing proximity and presence in our community's daily lives.
The dual edges of lithium-ion batteries
Lithium-ion batteries have become the leading technology for BESS and EVs due to their high energy density and efficiency. They enable the storage of large amounts of energy in relatively small spaces, making them a critical component of modern energy solutions. However, this technology also presents a safety risk because of its susceptibility to thermal runaway – a condition where battery cells enter an uncontrollable self-heating state. This can result in the deterioration of the battery or, in severe cases, combustion.
There are three main types of triggers for thermal runaway incidents:
- Mechanical abuse: Where there has been physical damage to the lithium-Ion batteries such as vibration, shock or impact.
- Electrical abuse: Short circuits, overcharging or over-discharging the battery.
- Thermal abuse: Subjecting batteries to extreme temperatures.
Batteries are particularly vulnerable during transport and handling, where physical impacts or exposure to extreme temperatures can compromise their integrity. Additionally, a deficient or absent battery management system can fail to detect and mitigate abnormal conditions, exacerbating the risk of thermal runaway.
The invisible threat
The leadup to a thermal runaway event can be gradual, presenting no visible signs. However, upon the onset of thermal runaway, the progression is rapid and can escalate to catastrophic failure, including fire and explosion, in seconds to minutes.
Thermal runaway fires continue to release energy, fuelled by the chemical reactions of the battery, making conventional mediums, such as water, ineffective for extinguishment. These fires are often self-sustaining due to the reactions producing their own oxygen.
Safety from the outset
While no technology is without risks, addressing safety from the start is crucial in project planning. Batteries used in BESS are classified as Class 9 Dangerous Goods when stored. A fire safety study undertaken in accordance with Hazardous Industry Planning Advisory 2 (HIPAP2) guidelines for such goods is essential from a safety perspective.
A fire safety study begins with identifying fire and explosion hazards specific to the site, taking into account the types and quantities of dangerous goods stored and the planned operations. The study then evaluates fire hazard scenarios in detail to assess whether the proposed fire safety systems – including provisions for fire brigade intervention – are adequate for the identified risks. If gaps are found, additional design recommendations are provided. This process can be iterative, meaning fire safety measures meet the desired standards before implementation.
For a large battery facility or one that handles a significant volume of batteries, the primary goal is to develop a design that is suitable to prevent the propagation of fire between BESS enclosures as well as surrounding infrastructure. This can be achieved through the incorporation of the following key strategies:
- Increased separation distances: Making sure there is sufficient space between BESS units and other structures to prevent the spread of fires.
- Passive fire construction: Using materials and designs that inherently resist fire to provide critical barriers.
- Active fire suppression systems: Implementing systems that can detect and control the spread of fire beyond the origin enclosure.
- Fire brigade intervention measures: Making sure emergency responders have the tools and information needed to manage incidents effectively.
In addition to fire risks, a buildup of flammable and toxic gas within a BESS enclosure may result in catastrophic deflagration or explosion events. Therefore, assessing the potential for dangerous pressure levels is essential, especially if large amounts of gas could ignite. Advanced modelling techniques, such as computational fluid dynamics, are critical for predicting and addressing these risks, helping to identify and mitigate potential problems before they arise.